Railway traffic controlling apparatus



Oct. l0, 1939.

H. A. THOMPSON E AL RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 27, 1938 5 Sheets-Sheet 1 VIL Oct. l0, 1939. H. A. THOMPSON ET AL 2,175,722

l RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 27, 19:58 "s sheets-sheet 2 INVENTOR S am AfIompson How Ralph Ifmm By Their ATToRNEY FMJN KON Oct. l0, 1939.

JAH @EAR 4 42 51' i 16 l5' 43] 577 J L p INVENTRS HowardATizompsoN Ralph Hemmer r By M Their ATTORNEY Patented Oct. 10, 1939 UNITED STATES PATENT OFFIC RAILWAY TRAFFIC CONTROLLING APPARATUS Application January v27, 1938, Serial No. 187,228

19 Claims.

Our invention relates to railway traffic lcontrolling apparatus of the class wherein coded track circuit energy is utilized to control either or both Wayside signals and train-carried cab signals, and more particularly it relates to the application of such apparatus to tracks in either electric or steam propulsion territory over which traffic may move in either direction.

One feature of our invention resides in novel provisions for enabling a single coding device having but one group of contacts to supply the rails of whichever one of two adjoining track sections carries authorized trailic toward the section junction with train-control energy which is coded in accordance with the traiic conditions beyond that junction. Another feature resides in a novel organization of circuits and apparatus which permits each coding device to supply energy to the rails of a plurality of different tracks. A further feature resides in an improved manner of controlling track relays of the centrifugal frequency-selective type in train-control systems of the type above named.

We shall describe several forms of railway traffic controlling apparatus embodying our invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic representation of a stretch of railway so track equipped with two-direction trafc-controlling apparatus embodying our invention.

Fig. 2 is a similar representation of the apparatus of Fig. 1 showing its condition when trailic movements are authorized in the reverse instead .f the forward direction. Fig. 3 is a representaf tion of a portion of one of the signal location equipments of the preceding figures showing the apparatus thereof interconnected in a modified manner, and Fig. 4 is a View showing a single code transmitter connected to supply train-control energy to the rails of a plurality of diiierent tracks.

Referring to the drawings, in the several views of which like reference characters designate corresponding parts, the improvements of our invention are there disclosed as being incorporated in a system of controlled manual block signaling for a stretch of track |-2 over which traiic may move in either direction, In describing the diagrams of these drawings, it will be assumed that the left end thereof is west and the right end east, and that forward traffic is eastbound and reverse trafc is westbound.

The rails I and 2 of the represented track are `divided by means of insulated joints 3 into a plurality of successive sections only one of which, F-G, is represented in each of the diagrams of Figs. 1 and 2. The particular stretch of track there shown is intended for use in a railway system employing electric propulsion, and for this 5 reason impedance bonds 4 of the customary form are provided at each pair of insulated joints to conduct propulsion current therearound. It will be apparent, however, that the apparatus of our invention is equally Well suited for use on a steam road, in which application the bonds 4 would, of course, be omitted, as in the showings of Figs. 3 and 4.

The rails of each of the referred to sections of track form a part of a track circuit through which train-control energy may be transmitted. Each of these track circuits further includes a pair of track transformers TT and 'TTI connected with the rails thereof at the east and west ends of the section, respectively, and a track relay TR having a control winding 1 which also is connected with the West ends of the section rails.

A suitable alternating-current source, designated in the diagrams by the terminals B and C, normally supplies, through transformer TT, the track circuit with steady or uninterrupted energy of suitable signal-power frequency, such as 50 or 100 cycles per second. As long as the section is vacant, this energy is transmitted by the rails to the winding 'l to maintain the track relay TR actuated. When, however, a train enters the section, the usual shunting action of its Wheels and axles deprives the relay of this steady energy, and thereby initiates control operations which cause coded energy, suitable for controlling traincarried cab signals, to be impressed between the rails.

Inv the particular arrangement disclosed, this coded energy is supplied to the east end of the track circuit through the transformer TT when the mentioned train is an eastbound one and to the West end of the circuit through the transformer TTI when the traic to be governed is Westbound. In consequence, cab signals carried by a train progressing through the section in either direction are controlled, in the desired manner, by the measure of this rail-transmitted energy which is received from a point ahead of the train by the usual inductive pick-up apparatus mounted on the locomotive front.

Use is made, during operation of the signaling apparatus under conditions of westbound traic authorization, of an impedance transformer TX and a code-following control relay CR to prevent the pulses of coded energy which the track transformer TTi at times supplies to the west or relayconnected end of the track circuit from falsely actuating the track relay TR. 'I'he primary winding of this transformer is included in the circuit of the track relay control winding 'l in the manner shown, and the secondary winding thereof is arranged to be shortcircuited or closed upon itself through a contact G of the relay CR at all times except when the transformer TTI supplies energy to the track rails. Through circuits later to be described, the relay CR is also energized during each period of such energy supply and caused to bias the named contact upwardly, thereby opening the secondary circuit of the transformer TX upon the occasion of each energy pulse.

With its secondary short-circuited, the transformer TX adds very little to the impedance of the track relay circuit and, under this condition, which is the normal one, the relay TR operates in the same manner as were the transformer not present. When, however, the secondary circuit is opened, the amount of added impedance is. increased so substantially as to prevent the track relay from being actuated by the potential which appears between the rails as a result of their energization from the transformer TTI In cer tain cases, moreover, that potential may have an instantaneous polarity which is opposite to that of the current which the winding 'l of relay TR normally receives from the track rails and in those instances it is customary to provide the track relay with means (not shown but one form of which is described in the following paragraph) which make it unresponsive to reverse energiza tion of any degree.

Each of the track relays represented at TR. is of the centrifugal frequency-selective type and in addition to the control winding 1 already described as being connected to the rails of the associated track circuit, it is provided with a local winding 3 which is arranged to receive energization from the alternating current source B-C. These two windings form a part of an induction motor which operates the relay contacts by rotating a flyball mechanism 9. As long as this mechanism is at rest, the contacts occupy their downward or unactuated positions. When, however, the device is rotated in a normal or forward direction, the yballs are moved outwardly by centrifugal action, and this movement is utilized to raise the relay contacts. To prevent the relay from responding to reverse energization of the character referred to in the preceding paragraph, the mechanism 9 is provided with a ratchet device (not shown) which permits the fiyballs to be rotated only in the normal or forward (and not in the reverse) direction.

The contacts reachtheirfully-actuatedorfrontclosed positions only when the speed of this rotation is of the high value which results when the relay windings are energized from the 60 or 100 cycle supply circuit B-C. As any energy of the conventional 25 cycle electric propulsion frequency which may accidentally enter the relay, as under unbalanced track circuit conditions, is incapable of producing the critical speed above referred to, false contact closure, in electrified territory applications, due to stray propulsion current thus becomes impossible.

Coding of the train-control energy supplied at proper times to the trackway through one or the other of the track transformers TT or TTI is effected at each of the section-division locations F, G, etc. by a code transmitter CT there installed in the manner indicated. Each of the transmitters shown by way of illustration is provided with three circuit making-and-breaking contacts 80, |20 and |80 arranged for selective inclusion in the energizing circuit of one or the other of the two transformers just referred to. During operation of the transmitter, these contacts are continuously actuated by a motor or other suitable mechanism (not shown in detail) at three different speeds which for purposes of explanation will be assumed to be such as respectively to provide slow, caution and proceed codes of 80, 120 and 180 energy pulses per minute.

Also installed at each section-division location are a pair of relays ET and WT through the medium of which selection is made of the direction in which traffic is authorized to move through the protected stretch of track. When the relays ET at all of the locations are actuated and all of the relays WT are deenergized, the apparatus is set up to authorize and control trafc movements in the eastbound direction. Similarly, when the relays WT at all of the locations are actuated and the relays ET are deenergized, the apparatus is conditioned to authorize and control traffic movements in the westbound direction.

Circuits for controlling these direction-selecting relays are well known, and, since they form no part of the present invention, no attempt has been made to disclose them herein. Typically, however, they may be included in the controlled manual block system previously mentioned and when such is the case, block station operators at opposite ends of the protected stretch of track must first cooperate with each other to obtain the use of the stretch and must then set the relays ET and WT in positions appropriate for the selected direction of traic movement.

Additionally installed at each of the section' division locations is a relay AR which is arranged to connect the associated code transmitter CT with its energizing source B-C and to set up appropriate circuits for distributing the output thereof whenever a train approaches the location from either direction and to maintain the transmitter deenergized and the track transformer 'IT appropriately energized at all other times. These approach-control relays AR are normally energized from a suitable source of direct current potential, designated in the diagrams by the terminals plus and minus, through control circuits Which include track relay contacts I0 and Il, direction-selector relay contacts I 2, and location-interconnecting line conductors i3.

Further forming a part of the controlled manual block system previously referred to are wayside signals SE positioned adjacent the points of track section division and arranged to control eastbound traiiic through the protected stretch and other wayside signals SW similarly located along the trackway and arranged to govern west bound traffic. These signals may be of any suitable form and as here represented are of the semaphore type each capable of showing any one of the indications of proceed, caution, slow and stop.

Since the circuits for 'controlling these wayside signals form no part of the present invention, the details thereof are omitted from the drawings for the sake of simplicity. For present purposes, it is sufficient to state that three relays H, JA and J installed at each section division block are utilized to control the signals through connections which include contacts M of each associated direction-selector relay WT. When the relays WT are unactuated, as under conditions of eastbound traiTic authorization, the named contacts connect the named control relays with the eastbound signals SE and when the relays WT are actuated, as under conditions of westbound traiiic authori- Zation, the contacts I4 connect the control relays with the westbound signals SW.

In the particular arrangement represented all of the signals associated with the unauthorized direction of trafc continuously show stop and the signals associated with the authorized direction of traffic are controlled in well-known automatic block system manner by the relays H, JA and J. That is, all of these signals not under the control of a train show proceed while those at the first, second and third locations immediately behind a train respectively show stop, slow and caution.

The actuation of the relays H, JA and J which is necessary to effect the named form of signal control may be effected in any suitable manner through Well-known control circuits (not shown) which, typically, may include contacts of the track and direction-selecting relays and line conn ductors interconnecting the apparatus of adjacent signal locations. For purposes of explanation, it will be assumed that relay J is a polarized device and that the just-referred to circuits control it and the relays H and JA in the following manner.

When all sections of the protected stretch of track are unoccupied, all three of the relays are actuated, the polar contacts of relay J now being in the normal position. In the event that one of the sections becomes occupied by a train, all three of the relays at the traffic entering end thereof become deenergized and hence unactuated. At the next signal location to the rear, relay H only is actuated; at the third location behind the train relays J and JA are also actuated, the polar contacts of relay J now being in the reversed position; and at succeeding locations to the rear all three relays are actuated, the polar contacts of relay J now occupying their normal position.

In the improved arrangement of our invention, contacts I5 and I6, respectively, carried by the signal-control relays H and JA at each section-division location are utilized to select which one of the three codes of 80, 120 and 180 energy pulses per minute is distributed from the associated code transmitter CT. When both of the relays H and JA are actuated, the circuits are set upf to transmit the proceed or I 8E] code; when relay H is actuated and relay JA is unactuated the distributing circuits receive the caution or IZB code; and when both relays are unactuated, the circuits are set up to transmit the slow or 89 code.

Under conditions of eastbound traiiic authorization (see Fig. 1), energy of the particular coding thus selected is at proper times transmitted through a contact I8 of the approach control relay AR to the track transformer TT and also to the local winding 8 of the track relay TR at the signal location to the rear or west of the supplying code transmitter CT. The track transformer circuit then includes contacts I9 and 28 of the relays AR and ET and the track relay coding circuit then includes contacts 2i and 22 of relays AR and ET, a line conductor 23 which interconnects adjacent signal locations, and a contact 24 of relay ET at the westward or rear location.

Under conditions of Westbound traiiic authorization (see Fig. 2), energy of the selected coding is distributed at proper times from each code transmitter CT to the winding of the code following relay CR through a circuit which includes the previously referred to contact I8 of relay AR and a contact 26 o1 relay WT. Through a contact 28, the thus actuated relay CR supplies coded energy to the track transformer TTI and to the local winding 8 of the associated track relay TR. The Acircuit for eifecting the latter supply includes a contact 29 of the relay WT.

The Various component parts of our improved signaling apparatus having been described, attention will now be directed to the manner of operation of the complete system shown in the diagram of Figs. 1 and 2. As this operation is somewhat different when the trac to be governed is Westbound than when it is eastbound, separate explanation will be given for traflic movements in each of these two directions.

Attention Will first be directed to what takes place when the direction of authorized trafc movement is eastbound, as indicated by the diagram of Fig. l. In this case all of the eastbound selector relays ET are actuated and all of the westbound relays WT are deenergized. This causes all of the westbound signals SW to show stop and the eastbound signals SE to be controlled in automatic block system manner.

When all of the protected blocks are unoccup-ied, the control Winding 'l of each track relay TR receives steady energy from the rails of the associated or forward track section, and the local winding 8 of that relay also receives steady energy from a circuit which extends from supply terminal B at the next location to the east through front-closed contact 2I of relay AR at that advance location, conductor 3%, front-closed contact 22 of relay ET at the same advance 1ocation, line conductor 23, front-closed contact 24 of relay ET at the associated location, conductor SI and the winding 8 of relay TR back to the supply terminal C.

This causes all of the track relays to maintain their contacts in the front-closed positions. In consequence, all of the approach relays AR also receive energizing current through circuits which, in each case, may be traced as follows: from a positive supply terminal at the next location to the west, through iront-closed contact II of relay TR at that rearward location, line conductor I3, back-closed contact I2 of relay WT at the associated location, conductor 32, and the winding of the relay AR back to a negative supply terminal. As a result, these relays AR all hold their contacts in the upward or frontclcsed positions,

Under the named condition, the rails of the track section immediately behind or west of each signal location are supplied with steady energy through the track transformer TT. The track transformer energizing circuit may in each case be traced from a supply terminal B at the associated location through front-closed contact cupies one of the sections of the protected stretch of track, the wheels and axles thereof shunt the trackway potential from between the rails and deenergize the track relay TR which is connected thereto. This relay drops its contacts to their back positions as shown at location F in Fig, l, opening, at contact Il, the actuating circuit for the approach relay AR at the neXt location to the east. That relay now drops its contacts to their back positions, as shown at location G in Fig. 1.

Contact 36 of this approach relay now cornpletes a circuit which places the associated code transmitter CT in operation. This circuit extends from supply terminal B through the contact 3E, conductor 3l, and the operating winding of the transmitter back to supply terminal C. At the same time, contact 3E oi the relay AR connects the coding contacts 89, t28, and iil of the transmitter with another supply terminal B and contacts E8, 2i and 9 of the relay set up circuits through which energy coded by one of the transmitter contacts is distributed to the local winding B of the track` relay TR at the next location to the west and to the track transformer TT at the associated location.

The referred to energizing circuit for the transformer TT extends from a supply terminal B through back-closed contact 38 of relay AR, conductor 4S, coding contact iii? of the 'transmitter CT, conductor i, front-closed Contact i5 of relay JA, conductor 42, front-closed contact i5 of relay H, conductor 43, back-closed contact i8 of relay AR, conductor 44, back-closed contact i9 of relay AR, conductor 33, front-closed Contact 2*] of relay ET, conductor 311-, and the primary winding of transformer TT back to supply terminal C. The referred to energizing circuit for the local winding of the track relay TR at the next location to the rear may be traced from supply terminal B through Contact i of the code transmitter CT at the forward location, conductor 43, back-closed contact I8 of relay AR, conductors M and 45, back-closed contact 2i of relay AR, conductor 38, iront-closed contact 22 of relay ET, line conductor 23, front-closed contact 24 of relay ET at the rear location, conductor 3i, and the winding 8 of the rear-location track relay back to supply terminal C.

Through the transformer TT, the east or trafc-leaving end of the occupied track section is, in the manner described above, supplied with traincontrol energy of the E33 or proceed code. This energy causes current to circulate through the rails ahead of the wheels and axles of the eastbound train VE which current inductively transfers energy, through pick-up devices mounted on the locomotive front, to the 'train-carried control apparatus and causes the cab signals to show proceed, thereby indicating that the two track sections immediately ahead are unoccupied.

The rails of the section occupied by the train VE transmit no trackway energ to the rear of the train and the apparatus at the associated rearward signal location assumes the condition represented at F in Fig. l. There the westbound track transformer 'I'T is deenergized as is also the control winding 'l of the track relay TR. The local winding 8 of this relay receives energy of the [8U code through the circuit previously traced (which circuit includes eastwardly extending line conductor 23), which energy damps or retards any motion of the centrifugal mechanism 9 of the relay and thus hastens the opening of the contacts following the initial entry of the train into the track section. Approach relay AR holds its contacts in the front-closed position as a result of receiving actuating current through the previously-traced circuit which includes the front-closed contact il of the track rela-y TR at the next location to the west.

The code transmitter CT at the location under discussion accordingly remains unenergized, as represented at F, and the associated track transformer TT supplies steady energy to the rails of the track section to the rear as a result of the primary winding being connected with the source B-C through front-closed contacts It and 20 of relays AR and ET. The relays H, JA and J are all unactuated and cause the controlled signal to show the indication of stop, as displayed by device SEf. The now hack-closed contacts I5 and IG of relays H and JA set up a circuit, of which conductor l? forms a part, through which the code transmitter CT will supply the track transformer TT with energy of the 80 or slow code should a second train enter the section to the immediate rear.

At the second signal location behind the eastbound train VE, the condition oi the equipment is as follows: Both the control and local windings of the track relay TR receive steady energy and the relay holds its contacts in their frontclosed positions. Approach relay AR is also actuated and the code transmitter CT is unenergized. The rails of the track section to the rear are supplied with steady energy by Way of track transformer TT connected with source B--C through contacts i9 and 20 of relays AR and ET.

Relay H is actuated and relays J and JA are unactuated thereby causing the controlled signal SE to show slow and setting up, by means of contacts i5 and I6, a circuit, including conductor 46, through which the contact 23 of the code transmitter CT will supply the track transformer TT with energy of the IZB or caution code should a second train enter the section to the immediate rear.

At the third location behind the eastbound train VE, the equipment has the following condition: Both the track and approach relays TR and AR are actuated. Code transmitter CT is unenergized and track transformer TT supplies steady energy to the rails of the track section to the rear. Relays H, JA and J are actuated (polar relay J reversely), causing the controlled signal to show caution and setting up a circuit through which the code transmitter will supply the track transformer TT with energy oi the i8!) or proceed code should a second train enter the section to the immediate rear.

Finally at the fourth and at all succeeding signal locations (which are associated with unoccupied sections) behind the eastbound train VE, the condition of the equipment is as follows: The track and approach relays TR and AR are actuated. Code transmitter CT is deenergized and track transformer TT supplies steady energy to the rails of the track section to the rear. Relays H, JA and J are actuated (polar relay J normally) and cause the controlled signal to show proceed and set up a circuit through which the code transmitter will supply the track transformer TT with energy of the E36 or proceed code should a second train enter the section to the immediate rear.

Assume now that'while the rst eastbound train VE continues to occupy the section F-G of Fig. l, a second eastbound train (not shown) does approach from the rear. As this second train approaches the third, second and first track sections behind the first train, it will respectively receive from signals SEI the usual visual indications of proceed, caution and slow, and train-carried signals in the Cab of its locomotive will be caused to show corresponding indications as the train advances into the successive sections named. This comes about in the following manner.

In entering each section, the second train deenergizes the associated track relay TR thereby also deenergizing the approach relay AR at the signal location immediately ahead. This places in operation the code transmitter CT at that advance location and causes the associated track transformer TT to supply coded train control energy to the forward end of the section. For the third and succeeding sections behind the first train, this energy is, as has been seen, o-f the |80 or proceed code and for the second and first Vsections behind the one occupied by the first train, it is respectively of the |20 or caution code and the 80 or slow code.

As an eastbound train moves out of each track section, the following operations take place, The

n removal of the interconnection of the rails of the section allows these rails to transmit coded energy to the control winding of the track relay TR at the west end of the section and the local winding 8 of this relay continues to receive or two code pulses brings it up to full speed.

` Since both of the windings 'I and 8 are energized and deenergized simultaneously, the rotor 9 freely drifts during the 01T code periods and is free from the damping action which would l be present were one of the windings to remain energized continuously.

The resulting front closure of the track relay contacts reestablishes, at contact Il, the energizing circuit for the approach relay AR at the next location east. That relay now actuates its contacts to their upward positions to effect the following actions: Contacts 36 and 38 shut down the code transmitter CT at the forward location; contact I9 connects the associated track transformer TT with its source of steady energization B-C; and contact 2| reestablishesl the circuit, of which line conductor 23 forms a part, through which steady energization is supplied to the local winding 8 of the track relay TR at the rear location. The mentioned track transformer TT now supplies steady energy to the associated track rails and thereby maintains the track relay at the rear location in its normally actuated condition.

All portions of the train-control apparatus are now restored to the unoccupied-track-section condition. The operations described above, which are incident to such restoration, proceed with great rapidity, the total time required therefor typically being of the order of only a second or two.

jthe direction of authorized traffic movement is west, as represented by the diagram of Fig. 2. In this case, all of the westbound direction selector relays WT are actuated and all of the eastbound relays SEI are unenergized, thereby caus- 7.5, ing all of the eastbound signals SE to show stop and the westbound signals SW to be controlled in automatic-block-system manner.

When all of the protected blocks are unoccupied, the condition of the control equipment at each of the signal locations is as follows: The track relay TR maintains its contacts in the front-closed positions as a result of its control Winding 'l receiving steady energy from the rails of the associated or eastward track circuit and of the local winding 8 also receiving steady energy. The local-winding supply circuit now extends from supply terminal B, through backclosed contact 28 of relay CR, conductor 48, front-closed contact 29 of relay WT, conductor 3|, and the relay winding 8 back to terminal C. T'he approach relay AR also maintains its contacts in the upwardly actuated positions as a result of receiving energizing current through a circuit which extends from a positive supply terminal, through front-closed contact I of relay TR, conductor 50, front-closed contact i2 of relay WT, conductor 32 and the relay winding back to a negative terminal. All three of the relays I-I, JA and J are actuated (polar relay J normally) and each controlled wayside signal SW is thereby caused to give the clear or proceed indication.

At all times that westbound movement is authorized, the track transformer TT at each location continuously supplies the rails of the track section immediately to the west with steady energy. Under these conditions the transformer energizing circuit extends from supply terminal B, through back-closed contact 20 of relay ET, conductor 34 and the primary winding of the transfo-rmer back to terminal C. At no time is this circuit interrupted, in the arrangement shown, as long as the authorized direction of movement continues to be westbound.

In the event that a westbound train VW occupies one of the sections of the protected stretch of track, the wheels and axles thereof shunt the trackway potential from between the rails and deenergize the particular track relay TR which is connected thereto. This relay drops its contacts to their back positions, as shown at F in Fig. 2, and opens, at contact I0, the actuating circuit for the approach relay AR, causing that relay also to drop its contacts to their back positions.

Contacts 36 and 38 of relay AR now complete energizing circuits for the code transmitter CT and contact |8 sets up a circuit through which the transmitter supplies coded energy to the winding of code-following relay CR. This circuit extends from supply terminal B, through back-closed contact 38 of relay AR, conductor 40, coding contact |80 of device CT, conductor l i, front-closed contact I6 of relay JA, conductor 42, front-closed contact l of relay H, conductor 153, back-closed contact I8 of relay AR, conductor 5|, front-closed contact 26 of relay WT, conductor 52 and the winding of the relay back to terminal C.

Upon each pulse of coded energy thus received, relay CR actuates its contacts to their upward positions and during each period of deenergization which follows allows them to return to their back-closed positions. Contact 28 thus causes the transformer TTI to be supplied with correspondingly spaced pulses of energization by periodically completing a circuit which extends from supply terminal B through the contact 28 (in its front-closed position), conductor 53 and the primary winding of the transformer back to a supli I) ply terminal C. This same Contact also causes the local winding 8 of the track relay TR to be supplied with similarly coded energy by periodically completing a circuit which extends from supply terminal B, through the contact 28 (in its back-closed position), conductor 8, frontclosed contact 29 of relay WT, conductor 3l and the Winding 8 back to terminal C.

In the manner described above, the trafficleaving end of the occupied track section .is supplied with train-control energy of the |80 or proceed code. Due to the before-explained action of the impedance transformer TX and the contact 3 of relay CR, the track relay TR is prevented from being falsely operated by this energy and remains continuously unactuated as long as the associated track section is occupied. It Will also be noted that the interruptions of the energizing circuit for the local winding 8 of the track relay TR, which contact 28 of relay CR effects coincide with the pulses of coded train-control energy which are supplied to the trackway through transformer TTI. This further safeguards the track relay against false actuation of the character referred to bove. Moreover, in the event that the energy from transformer TTI is of the reversed relative instantaneous polarity discussed in an earlier portion of this specification, the reverse-rotatifin-preventing ratchet mechanism (not shown) of relay 'IR then absolutely prevents response regardless of what the magnitude of that energy may be.

At the first signal location behind or to the east of the westbound train VW, the apparatus assumes the condition represented at G in Fig. 2. There the track relay TR is actuated by steady energy received from the rails of the associated track circuit, the approach relay AR also holds its contacts in their upward positions, the -code transmitter CT is not operating, the code-following relay CR is unactuated, and the track transformer TT supplies steady energy to the rails of the occupied section. Contact 28 completes the steady energizing circuit for the local winding of relay TR and interrupts the primary circuit of the track transformer TTI. The relays H, JA and J are all unactuated and cause the controlled signl to show stop. The back-closed contacts I5 and I6 of relays I-I and JA now set up a circuit through which the code transmitter CT Will supply the relay CR with energy of the 8D or slow code should a second train enter the section to the immediate rear.

At the second signal location behind the train VW, the condition of the equipment is as follows: Both the control and local windings of the track relay TR receive steady energy and the relay holds its contacts in their front-closed pesitions. Approach relay AR is also actuated, the code transmitter CT is unenergized, the code-following relay CR is unactuated, the track transformer TT supplies steady energy to rails of the forward track section, and the primary circuit of the track transformer TTI is interrupted at contact 28. Relay H is actuated and relays J and JA are unactuated, thereby causing the controlled signal SW to show, slow and setting up, 'through contacts I5 and IG, a circuit through which the contact I2!) of the code transmitter CT Will cause the track transformer TTI to be supplied with energy of the |20 or caution code should a train enter the section to the immediate rear.

At the third location behind the occupied section, the equipment assumes the following condition. Track relay TR is actuated. as is also appreach relay AR; code transmitter CT, relay AR, and track transformer TTI are unenergized; and the track transformer TT supplies steady energy to the rails of the track section in advance. Relays H, JA and J are actuated (polar relay J reversely) causing the controlled signal to show caution and setting up a circuit through which the code transmitter will cause the track transformer TTI to be supplied with energy of the 8S or proceed code should a second train enter the section to the immediate rear.

Finally, at the fourth and at all succeeding signal locations (associated with unoccupied sections) behind the westbound train VW, the condition of the equipment is as follows: The track and approach relays TR and AR are actuated, code transmitter CT, relay AR and track transformer TTI are unenergized, and the track transformer' TT supplies steady energy to the rails of the track section in advance. Relays H, JA and J are actuated (polar relay J normally) and cause the controlled signal to show proceed and set up a circuit through which the code transmitter will cause the track transformer TTI to be supplied With energy of the |80 or proceed code should a second train enter the section to the immediate rear.

Assume now that while the rst westbound train VW continues to occupy the section G-F of Fig. 2, a second westbound train (not shown) does approach from the rear. As this second train approaches the third, second and first track sections behind the first train it will respectively receive from the signals SW the usual visual indications of proceed, caution and slow and signals in its cab will be caused to show corresponding indications as the train advances into the successive sections named. This cornes about in the following manner.

In entering each section, the second train deenergises the associated track relay TR, thereby also deenergizing the approach relay AR at the same location. This places in operation the associated code transmitter CT and causes the track transformer TTI to supply coded train-control energy to the forward end of the entered secticn For the third and succeeding sections behind the rst train, this energy is of the I80 or proceed code and for the second and rst sectic-ns behind the one occupied by the first train it is respectively of the I20 or caution" and the 8G or slow codes.

As a Westbound train moves out of each track section the following operations take place. The removal of the interconnection of the rails of this section allows these rails to transmit steady energy from the track transformer TT at the east end of the section to the control winding 'I of the track relay TR at the west end. The local Winding 8 of this relay continues to receive energy coded by the contact 28 of relay AR and the pulses of this coded energy coincide with the periods of low impedance for the circuit through which the control winding 'l receives steady trackway energy. In consequence, rotation is imparted to the fly-ball mechanism 9 of the track relay-TR and Within the space of a very small number of code cycles the mechanism attains full speed.

The resulting front closure of the track relay contact reestablishes, at Contact ID, the energizing circuit for the relay AR. In actuating its contacts to their upward positions that relay shuts down the code transmitter CT and interrupts the energizing circuit for the winding of relay CR. Track transformer-TTI is now deenergized and track transformer TT at the west end of the section continues to supply steady energy over the rails to the control winding of the track relay TR. The local winding of this relay now also receives steady energy through the back-closed contact 28 of relay CR and, in all other respects, the condition of the equipment is that appropriate for the now unoccupied track section.

The above described operations incident to the restoration of the apparatus associated with each track section to normal or vacant condition upon the departure of a Westbound train from the section take place very rapidly so that, as in the case of eastbound restoration, the total time required typically is of the order of but one or two seconds only.

Referring now t0 Fig. 3, we have there represented the westbound track transformer TTI as being interconnected with the associated apparatus at each of the section-division locations in a manner which causes it to receive coded energy directly from the code transmitter CT instead of through the auxiliary circuit shown in Figs. l and 2 as including conductor 53 and the contact 28 of the code-following relay CR. In the arrangement shown in Fig. 3, the primary winding of the transformer is, through conductor 53, directly connected with the conductor 52 through which the code transmitter supplies en ergy to the actuating winding of the relay CR. Contact 28 of this relay now supplies coded energy only to the local winding of the track relay TR through conductor 48.

Operation of the apparatus when thus connected is essentially the same as that already explained for the equipment of Figs. l and 2. Each pulse of coded energy from the transmitter CT now simultaneously energizes the transformer TTI and the relay CR and the periods of deenergization of both of these devices are also simultaneous. When a westbound train vacates the associated section of track the apparatus restores itself to the unoccupied operating condition in exactly the same manner as that previously described.

It has been seen that the improved apparatus of our invention includes novel provisions whereby each code transmitter CT supplies, from but a single group of contacts -I2Il-I8Il, coded train-control energy to either of two track transformers TT and TTI, respectively, connected with opposing ends of track circuits which include the rails of adjoining sections of a two-direction running track I-2. This is a feature of great practical advantage in that it eliminates the need at each section-division location for duplicate transmitters or for duplicate sets of synchronously operated contacts in a single coding device.

In applications wherein a plurality of parallel tracks are involved, these advantages may be evenfurther extended, as shown in Fig. 4. In that figure, we have illustrated one manner in which each of the code transmitters CT may be arranged to supply coded train-control energy to equipment associated with more than one two` direction running railway track. By way of i1- lustration of this plural application, two tracks respectively consisting of rails I and 2 and rails OI and O2 have been represented.

Associated with each of these tracks at each point of section-division 3 is train-governing equipment (only partially reproduced in Fig. 4) of the character shown in the preceding iigures, In the arrangement of Fig.Y 4, a single coding device CT supplies its coded energy to distributing conductors 55, 56 and 51 which transmit it to the code selecting circuits (which include contacts I5 and I6 of the relays H and JA) of corresponding equipment for each of the several different tracks. Through similarly arranged control conductors 59 and S, the contacts 36 and 38 of the approach relay AR included in the equipment associated with each and every one of the tracks may initiate and maintain operation of the transmitter CT.

Such operation, of course, makes coded energy available to all of the selecting circuits just reierred to as including relay contacts I5 and I6. Unless, however, such energy is actually needed, as evidenced by an unactuating condition of the approach relay AR, the distributing circuit (which includes conductor 43) remains open at contact I8 and the energy is not transmitted to the train control a'ppparatus. It will thus be seen that in the improved arrangement of our invention the number of tracks which can be supplied from a single code transmitter is limited only by the capacity of the coding contacts thereof.

While we have described our invention as being incorporated in apparatus which supplies only three train governing codes to the trackway and which forms a part of a controlled manual block system, it will be understood that our improved equipment may readily be adapted to other applications wherein provision is made for either more or less than three different train-governing indications.

Likewise, while we have restricted our disclosure to train-control systems employing track relays of a particular frequency-selective form especially suited for connection to electric propulsion tracks, it will be apparent that the broad improvements of our invention are equally applicable to train-control systems employing track relays of other types.

Although we have herein shown and described only a few forms of railway traiic controlling apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

l. In combination, a section of railway track,

a track relay provided with a control winding connected to the track rails at one end of said section and with a local winding, means for supplying steady alternating-current energy to said rails at the opposite end of the section at all times and to said local winding when the section is vacant, and a coding device rendered effective by said track relay when a train occupies the section and adapted at such times to supply coded alternating-current energy to said local winding and to the track rails at the relay connected end of the section.

2. In combination, a section of railway track, a track relay provided with a control winding connected to the track rails at one end of said section and with a local winding, means for supplying steady alternating-,current energy to said rails at the opposite end of the section at all times and to said local winding when the section is vacant, a coding device rendered eiective by said track relay when a train occupies the section and adapted at such times to supply coded energy to the track rails at the relay-connected end of the section and to said local wind- 7,51;

ing, and means for increasing the impedance of thc control winding circuit of the track relay during each pulse of said coded energy.

3. In combination, a section of railway track, a track relay provided with a control winding connected to the track rails at the traffic-leaving end of said section and with a local winding, circuits for continuously supplying steady energy to said rails at the traffic-entering end of the section and to said local winding, a coding device, means rendered effective by said track relay for placing said coding device in operation when a train occupies the section, and means responsive to said operation for supplying coded train-control energy to said rails at the trafiicleaving end of the section and for interrupting the energizing circuit for the local winding of the track relay during each pulse of said energy.

4. In combination, a section of railway track,

a track relay provided with a control winding connected to the track rails at the traffic-leaving end of said section and with a local winding, circuitsfor continuously supplying steady energy to said rails at the traffic-entering end of the section and to said local winding, a coding device, means rendered effective by said track relay for placing said coding device in operation when a train occupies the section and causing it to supply coded train-control energy to said rails at the traino-leaving end of the section, and a code-following relay energized by said coding device and adapted to increase the imped ance of the control-winding circuit of the track relay and to interrupt the energizing circuit for 1 the track relay local winding `during each pulse of said train-control energy.

5. In combination, a section of railway track, a track transformer connected to the rails thereof at the traffic-entering end of the section and l arranged continuously to supply steady energy thereto, a second track transformer connected with said rails at the traino-leaving end of the section, a track relay provided with a control winding also connected` to said rails at the trafc-leaving end of the section and with a local winding, a coding device, an approach relay controlled by said track relay and adapted to connect said local winding with a source of steady energy when the section is vacant and to place said coding device in operation when a train occupies the section, and a code-following relay energized from said coding device and adapted at such times to cause coded train-control energy to be supplied to said second-named track transformer, to increase the impedance of the control winding circuit of the track relay during each pulse of said energy and to interrupt the energizing circuit for the local winding of the track relay during each of said pulses.

6. In combination, a section of railway track, a coding device, a track relay having a control winding connected with the rails of said section and a local winding, an approach relay con-- trolled by said track relay, means including said lapproach relay for causing said coding device to supply coded train-control energy to said rails when a train occupies the section, a codefollowing relay controlled by said coding device, and means including said code-following relay for supplying coded energy to the local winding of said` track relay and for increasing the impedance of the control winding circuit of the track relay in step with the pulses of said coded energy.

'7. In combination, a section of railway track, a track relay provided with a control winding connected to the rails of said section and with a local winding, means eiective when the section is vacant for supplying steady alternatingcurrent energy to said local winding and to said rails, and a coding device rendered effective by said track relay when a train occupies the section and adapted at such times to supply coded alternating current energy to said local winding and to said rails at the traino-leaving end of the section.

8. In combination, a section of railway track, a track relay provided with a control winding connected to the rails of said section at the trafo entering end thereof and with a local winding, circuits for supplying steady energy to said rails at the traffic-leaving end of the section and to said local winding, a coding device, and an approach relay controlled by said track relay and adapted to include said coding device in said rail and local winding supply circuits when a train occupies the section.

9. In combination, a section of railway track, a track relay provided with a control winding connected to the track rails at the traino-entering end oi' the section and with a local winding, circuits for supplying steady energy to said local winding and to the section rails at the trafcleaving end of the section, a coding device, and an approach relay controlled by said track relay and adapted to place said coding device in operation and include it in said local winding and rail supply circuits when a train occupies the section.

10. In combination, a section of railway track, a track transformer connected to the rails thereof at the trafiic-leaving end of said section, a track relay provided with a control winding connected to the track rails at the trahie-entering end ci said section and with a local winding, a coding device, and an approach relay controlled by said track relay and adapted to connect said track transformer and said local winding with a source of steady alternating-current energy when the section is vacant and to place said coding device in operation and include it in the energizing circuits of said transformer and of said local winding when a train occupies the section.

ll. In combination, a stretch of railway track divided into a plurality of sections, a track relay located at each point of junction of adjacent sections and connected near that point with the rails of the particular one of the there-adjoining sections which is on a given side of said point, each of said track relays being adapted to respond to the entry of a train into the section with which the relay is connected, a coding device also installed at each of said points of track section division and having but a single group of coding contacts, means for causing each of said coding devices to be rendered operative by the track relay at the location of the device when a train approaches that location from the said side of the relay-connected section and to be rendered operative by the track relay which is connected with the remote end of the other there-adjoining section when a train approaches the location from the opposing side of that other section, and means including the said coding-device contacts for supplying train-control energy to the devicelocation end of whichever of said two there-adjoining sections is between the location and the approaching trafiic and over which said traic must pass in reaching the location of said device.

l2. In combination, a stretch of railway track divided into a plurality of sections, a coding device located at each point of junction of adjacent sections and having a single group of contacts adapted to code trackway energy at one or another of a plurality of different rates, a track relay also installed at each of said points of track section division connected near that point with the rails of the particular one of the there-adjoining sections which is on a given side of said point, each of said track relays being adapted to respond to the entry of a train into the section with which the relay is connected, direction-selecting means for causing each of said coding devices selectively to be rendered operative by the track relay the same own location or by the track relay at the remote end of the opposing track section, a plurality of signal-control relays operatively associated with each of said track relays and actuated in accordance with traic conditions in advance of their location, and means governed by said signal-control relays and including the contacts of the coding device at each location for supplying energy of one or another of said different codes to the rails of the particular one of the two location-adjoining track sections which is between the location and the approaching traffic and over which said trailic must pass .in reaching said location.

13. In combination, plurality of railway tracks each of which includes a pair of successive sections which adjoin at approximately the same location along the right-of-way, tramo-governing equipment associated with each pair of the said parallel adjoining sections of said different tracks, a single code-transmitter installed at the said common location of track section junction and having but a single group of coding contacts, and means including said contacts for supplying coded energy to the rails of any one of the said parallel adjoining sections of any one of the said tracks.

14. In combination, a plurality of railway tracks each of which includes a pair of successive sections which adjoin at approximately the same location along the right-of-.vay, traiiic-governing equipment associated with each pair of the said parallel adjoining sections of said diierent tracks, a single code-transmitter installed at the said common location of track section junction and having an operating mechanism and but a single group of contacts, means including said contacts for supplying coded energy to the rails of any one of the said parallel adjoining sections of any one of the said tracks, and means forming a part of each or said trahie-governing equipments for controlling the operating mechanism of said transmitter.

l5. In combination, a section of railway track through which traffic may move either in a normal direction or a reversed direction, a rst circuit by way of vv ich the rails of said section may be supplied with energy at the end thereof which marks the exit for normal direction tranc, a second circuit by of which said rails may be supplied with energy at the end of the section which marks the exit for reversed direction traffic, i'lr t and second coding devices respectively located at said. rstcircuit and said second-ceuit of the section, rst and second approach relays for respectively governing the operation of irst and second coding devices, a track relay connected to receive energy from said rails at of said section ends, means eiective under all unoccupied conditions of the section for connecting one of said rail supply circuits with a source of uncoded energy thereby to maintain said track relay picked up whenever the section is vacant, direction-selector relays for determining whether authorized tralc through the section shall be in said normal direction or in said reversed direction, means including said selector relays for causing said track relay to control said first approach relay when trac in said normal direction is authorized and to control said second approach relay when traffic in said reversed direction is authorized, means eiective under said conditions of normal direction authorization and including said first approach relay for cmg said rst coding device in operation upon rac-.ase of track relay and for causing said circuit then to supply said rails with energy .oh is coded by that device, and means efective under said conditions of reversed direction authorization and including said second approach 'for placing said second codingdevice in operation a release of said track relay and for causi said second circuit then to supply said rails with energy which is coded by that device.

16. In combination, a section of railway track through which traflic may move either in a normal direction or in a reversed direction, a first circuit by way of which the rails of said section may be supplied with energy at the end thereof which marks the exit for normal direction traic, a second circuit by way of which said rails may be supplied with energy at the end of the section which marks the exit for reversed direction traffic, rst and second coding devices respectively located at said first-circuit and said second-circuit ends of the section, rst and second approach relays for respectively governing the operation of said first and second coding devices, a track relay connected to receive energy from said rails at one of said section ends, means eiective under all unoccupied conditions of the section for connecting one of said rail supply circuits with a source of uncoded energy thereby to maintain said track relay picked up whenever the section is vacant, direction-selector relays for determining whether authorized trafc through the section shall be in said normal direction or in said reversed direction, means including said selector relays for causing said track relay to control said rst approach relay when traic in said normal direction is authorized and to control said second approach relay when traffic in said reversed direction is authorized, means effective under said conditions of normal direction authorization and including said first approach relay for placing said first coding device in operation upon a release of said track relay and for causing said i'lrst circuit then to supply said rails with energy which is coded by that device, means effective under said conditions of reversed direction authorization and including said secon-d approach relay for placing said second coding device in operation upon a release of said track relay and for causing said second circuit then to supply said rails with energy which is coded by that device, and means for increasing the impedance of the said connection of said track relay with said rails during each pulse of the coded energy with which said rails are supplied at the section end where said track relay connection is made.

17. In combination, adjoining first and second sections of railway track over Which traic may move either in a normal direction of from said first to said second section or in a reversed direction of from said second to said first section, a coding device installed at the point of junction of said two sections and having but a single group of contacts, an approach relay for governing the operation of said device, a first circuit through which energy may be supplied to the rails of said iirst section at the end thereof which adjoins the second section, a second circuit through which energy may be supplied to the rails of said second section at the end thereof which adjoins the rst section, a i'irst track relay connected to receive energy from the rails of said first section and adapted to release whenever that section becomes occupied, a second track relay connected to receive energy from the rails of said second section and adapted to release whenever that section becomes occupied, direction-selector relays for determining whether authorized traffic through the sections shall be in said normal direction or in said reversed direction, means including said selector relays for causing said rst track relay to control said approach relay when traffic in said normal direction is authorized and for causing said second track relay to control said approach relay when traiic in said reversed direction is authorized, means effective under said conditions of normal direction authorization and including said approach relay for placing said coding device in operation upon a release of said rst track relay and for causingsaid rst circuit then `to supply said Iirst-section railsI with energy which is codedY by the said contacts of said device, and means effective under said conditions of reversed direction authorization and also including said approach relay for placing said coding device in operation upon a release of said second track relay and for causing said second circuit then to supply said second-section rails with energy which is coded by the said contacts of said device.

18. In combination, adjoining first and second sections of railway track over which traiiic may move either in a normal direction of from said iirst to said second section or in a reversed direction of from said second to said first section, a coding device installed at the .point of junction of said two sections and having but a single group o contacts, an approach relayfor governing the operation of said device, a first circuit through which energy, may be supplied to the rails of said first section at the end thereof which adjoins the second section, a second circuit through which energy may-be supplied to the rails of said second section at the end thereof which adjoins the first section, a first track relay connected to receive energyfrom the rails of said first section and adapted to release whenever that section becomes occupied, a second track relay connected to receive energy from the rails of said second section at the said end i thereof which adjoins the first section and adapted to release whenever that section becomes occupied, direction-selector relays for determining whether authorized traflic through the sections shall be in said normal direction ,or in said reversed direction, means including said selector relays for causing said first track relay -to control said approach relay when traic in said normal direction is authorized and for causing said second track relay to control said approach relay when traffic in said reversed direction is authorized, means effective under said conditions of normal direction authorization and including said approach relay for placing said coding device in operation upon a release of said iirst track relay and for causing said rst circuit then to supply said first-section rails with energy which is coded by the said contacts of said device, means effective under said conditions of reversed direction authorization and also including said approach relay for placing said coding device in operation upon a release of said second track relay and for causing said second circuit then to supply said second-section rails with energy which is coded by the said contacts of said device, and a code following relay eiective upon supply of energy through said second circuit to said second section to increase the impedance of the rail connecting circuit for the associated track relay during each pulse of said energy.

19. In combination, adjoining first and second sections of railway track over Which tralhc may move in either direction, a first wayside signal at the point of junction of said sections lor governing traiiic moves in one direction, a second wayside signal at the saine location for governing traffic moves in the opposite direction, a code transmitter also installed at said junction point and having but a single group of contacts, an approach relay for governing the operation of said transmitter, traffic responsive relays for governing the operation of one or the other of said wayside signals and for determining which of the contacts of said transmitter group is to be the active coding member, rst and second circuits through which energy may respectively be supplied to the rails of said first and second track sections, a first track relay responsive to the entry of a train into said first section, a second track relay responsive to the entry of a train into said second section, direction-selector relays for establishing the direction that traii'ic is authorized to move through said sections, means including said directionselector relays for selecting the wayside signal that said traflic responsive relays are to govern and for setting up a connection of said active-determined coding contact with the rail supply circuit for the particular one of said two sections over which traflic in the authorized direction must approach the point of section junction, and means including said direction-selector relays and said approach relay and effective upon a release of the track relay which is associated v `with said established section of traffic approach to cause a completion of the aforesaid set up connection and a placement in operation of said code transmitter contacts whereby the rails of said section of traffic approach Will receive coded energy which is suitable for controlling train carried cab signals.

HOWARD A. THOMPSON'. RALPH R. KEMMERER.

CERTIFICATE OF CORRECTI ON Patent No. 2,175,722. OctoberrlO, 19,39.

HOWARD A. THOMPSON, ETIAL.

- It is hereby certified that error ppearsin the printed specification of the above numbered 'patent requiring correction as follows: Page 9, first column, line l5, claiml2, for the words "the same own" read vat the same; v

and that the said Letters Patent should be read with this correction therein 'tht the same may-conform to the record of the case in the Patent office.

Signed and sealed this 7th day of November, A. D. 195.9.

Henry Van Arsdale (Seal) Acting Commissioner of Pgtents. 

